Dehazing polymer-containing hydrocarbon oils



awn-s United States Patent Delaware No Drawing. Filed July 17, 1961, Ser. No. 124,389 12 Claims. (Cl. 4462) The present invention relates to a process and composition for improving the water tolerance characteristics of hydrocarbon oils. More particularly, the instant invention concerns petroleum fuels and oils having incorporated therein additives to reduce the persistent haze and stable emulsions formed when such fuel products having haze-promoting polymeric additives incorporated therein are contacted with water.

Sludge, sediment, and other insoluble degradation products of hydrocarbon products having a tendency to clog fuel lines, orifices, screens and filters of fuel consuming engines have been dispersed by the use of oil soluble polymeric dispersants incorporated in the hydrocarbon product. These polymeric dispersants, while desirable from the standpoint of oil stability, have given rise to severe water tolerance problems. Polymeric additives exhibit particularly pronounced tendencies to suspend any water with which the oil containing these polymeric additives comes into contact, giving rise to very persistent aqueous haze and stable water-in-oil emulsions in the product. Since an aqueous phase exists in most storage tanks, pipelines, and other vessels, and contact and agitation of the water-oil occurs during the handling, transportation and storage of oil, haze formation and emulsification is almost impossible to avoid. As a consequence, the marketability and consumer acceptance of distillate fuels, jet fuels, heating oils, lu bricating oils, transformer oils, turbine oils, and other petroleum products in which polymeric dispersants are employed either as stabilizing, dispersant, detergent additives or for other purposes, is often seriously and adversely affected.

An object of the present invention is to reduce the tendency of certain hydrocarbon oil compositions containing haze-promoting additives, from forming persistent haze and stable emulsions when contacted with water. A further object is to promote the marketability of petroleum fuel products by inhibiting the persistent aqueous haze-promoting tendency of commonly employed oil soluble, ashless polymeric additive materials incorporated in the fuel. Other objects and the scope of the invention will be apparent from the following discussion and examples.

The applicant has discovered that the incorporation into hydrocarbon oil compositions of a minor amount of an alkyl pyrrolidone will inhibit the formation or reduce the persistent aqueous haze and stable water-in-oil emulsions induced by haze-promoting oil soluble polymeric additives. It has been found that these alkyl pyrrolidones are particularly effective in petroleum fuel compositions containing ashless, oil soluble polymeric dispersants. More particularly, the N-alkyl pyrrolidones have been found to be especially effective and may be incorporated into the hydrocarbon oil either before or after the contacting of water by the said oil. These pyrrolidones may be utilized in combination with the polymeric additives in a concentrate form or added singly into the hydrocarbon oil. The pyrrolidones suitable for the purposes of this invention include those alkyl substituted pyrrolidones wherein the alkyl radical has from about 1 to 4 carbon atoms. Preferred due to their ice efiicacy are the N-alkyl substituted pyrrolidones, while especially preferred by reason of commercial availability and performance are the N-alkyl beta pyrrolidones, such as N-methyl-Z-pyrrolidone. It should be noted that the employment of pyrrolidone itself is not fully suitable for the purposes of this invention due to its restrictive and limited solubility in hydrocarbon oils. The applicant has found that his inventive compounds exhibit a suitable water-oil solubility balance such that effective dehazing is accomplished.

The exact quantity of the inventive pyrrolidones required to reduce haze to a minimum or to inhibit a fuel against the formation of haze depends to some extent on the particular polymeric additive employed, concentration level of the polymeric additive, the severity of the mixing of the oil and water, and the amount of water present. Most of these factors are subject to control or may be ascertained, whereby the concentration level of the alkyl pyrrolidone required may be estimated or determined by simple experimentation well Within the capabilities of a person skilled in the art. Usually minor amounts of pyrrolidones are effective, such as from about 0.1 to 5.0% by volume, with from 0.5 to 3.0% by volume normally effective. The addition of sufficient alkyl pyrrolidone to yield a light transmission of above after about 1% Water contact, for example, after a two hour settlement period as set forth in the Waring Blendor test is the preferred concentration level employed. The addition of excessive quantities of alkyl pyrrolidones over that amount required for the degree of protection sought or for clarification of the haze condition should generally be avoided since it may result upon subsequent vigorous agitation is a degradation of the desired haze condition. The weight ratio of alkyl pyrrolidone to polymeric additive may range from 50/1 to 2/ 1.

Suitable pyrrolidones for the purposes of this invention include the following: 3 methyl N-methyl-Z-pyrrolidone, 4-ethyl-N-ethyl-l-pyrrolidone, N-ethyl-l-pyrrolidone, 3-methyl-2-pyrrolidone, 2,3-dimethyl-N-methyl-l-pyrrolidone, N-methyl-Z-pyrrolidone, and the like.

The polymeric dispersant additives primarily responsible for the poor water tolerance of hydrocarbon oils and similar products are widely used commercially and are well known to those skilled in the art. These dispersants in general are polymers and copolymers of unsaturated organic esters, nitriles and similar organic polymerizable monomers, such as ethylenically unsaturated monomers containing one or more vinyl, vinylene, or vinylidene linkages per molecule. These oil soluble ashless polymers, copolymers and terpolymers generally have molecular Weights ranging from 1000 to 100,000, and preferably from 6000 to about 20,000 Staudinger,

V and are employed in hydrocarbon oils in minor amounts as detergents, sludge inhibitors, stabilizers, and the like.

A class of polymeric dispersant additives in conjunction with which the pyrrolidones of this invention have been found to be effective are those which are prepared by the copolymerization of an alkyl chloropropyleneoxy mixed ester of an unsaturated conjugated dibasic acid with a polymerizable organic monomer containing a vinylidene linkage. These copolymers are described in US. application Serial No. 673,156, filed July 22, 1957, and

now abandoned, which is hereby incorporated by reference.

A second class of polymeric dispersant additives with which the pyrrolidones are also effective are oil-soluble, nitrogen-containing addition type copolymers prepared by copolymerizing an amine-free monomer containing one polymerizable ethylenic linkage and an aliphatic hydrocarbon chain of from 8 to 18 carbon atoms with a monomer containing a nitrogen atom and one polymerizable ethylenic linkage. Such copolymers may be prepared, for example, by the copolymerization of an acrylic or alpha-substituted acrylic ester of an aliphatic alcohol containing an average of from 8 to 18 carbon atoms, such as lauryl methacrylate, With-an ethylenically unsaturated compound containing a basic amino group, such as beta dimethylamino-ethyl methacrylate. These copolymers are more fully described in U.S. Patent 2,734,452 and U.S. application Serial No. 711,067, filed January 24, 1958.

An additional class of commercial polymeric dispersants especially useful as V1. and detergent additives to lubricating oils which give rise to water tolerance problems is obtained by the polymerization of from 1 to mole percent of an ethylene unsaturated dicarboxylic acid or anhydride such as a butenedioic acid or anhydride, like maleic anhydride, with from 20 to 40 mole percent of an alkyl C C ester of an 1x43 unsaturated dicarboxylic acid such as ditallow fumarate, di-C -OXO fumarate and the like; and from 40 to 80 mole percent of a copolymerizable alkylene ester of an aliphatic C -C monocarboxylic acid such as vinyl acetate. These terpolymers are more fully described in U.S. application Serial No. 754,153, filed August 11, 1958.

Another polymeric additive agent described in U.S. application Serial No. 807,987, filed April 22, 1959, comprises the oil soluble copolymer obtained by the reaction of from 70 to about 99% by weight of alkyl C C acrylate and methacrylate esters, such as lauryl methacrylate, with from 1 to about by weight of an N-vinyl pyrrolidone, such as 5,5-dimethyl-N-vinyl pyrrolidone. These copolymers employed in hydrocarbons are also improved in water tolerance characteristics by the additives of the invention.

A further class of polymeric oil soluble additives which tends to promote haze is the terpolymers as described in U.S. application Serial No. 769,991, filed October 28, 195 8. These terpolyrners are prepared by the reaction of from 25 to 60 mole percent of a long chain aliphatic ester of an unsaturated conjugated C to C dibasic acid (preferably a butanoic acid), such as lauryl fumarate; 15 to 65 mole percent of a vinyl ester of a short chain fatty acid, such as vinyl acetate; and 5 to mole percent of an N-vinyl amide, such as N-vinyl pyrrolidone.

Further oil soluble commercial copolymers and terpolymers which degrade the water tolerance characteristics of the hydrocarbon oil in which they are incorporated are those terpolymers as described in U.S. application Serial No. 754,313, filed August 11, 1958.

Polymeric dispersant additives as above described are sometimes employed in combination with tertiary alkyl primary amines. Although such amines do not have pronounced dispersant properties, they effect a considerable improvement in the stabilizing action of the nitrogencontaining polymeric dispersants. They do not, however, overcome the tendency of such dispersants to suspend water in oils in which they are present and hence do not prevent the water tolerance problem caused by the dispersants. The alkyl pyrrolidones may therefore be employed to advantage in oils containing both a polymeric additive and a tertiary alkyl primary amine.

The tertiary alkyl primary amines useful with the polymeric dispersants described above in general are those having two alkyl groups of from 1 to 3 carbon atoms attached to the tertiary carbon atom and one alkyl group of from 5 to 21 carbon atoms attached to the tertiary carbon atom. Tertiary alkyl primary amines containing a total of from 8 to 18 carbon atoms per molecule are preferred. Particularly preferred are C tertiary alkyl primary amines. Mixttu'es of such amines such as those derived from polyolefins may also be used.

Tertiary alkyl primary amines such as those described above are generally employed in combination with the polymeric dispersants in concentrations such that the ratio of amine to dispersant in the oil ranges from about 2 to 1 to about 18 to 1. Amine concentrations between about 0.003 wt. percent to about 0.8 weight percent are especially effective.

Many other polymeric dispersant additives suitable for the stabilization of hydrocarbon oils will be familiar to those skilled in the art. The stabilization of haze and emulsions is a universal characteristic of such polymeric additives and the alkyl pyrrolidones may be employed With a wide variety of such polymeric materials. Representative examples of other ashless, oil soluble polymeric stabilizing additives are described in U.S. Patent 2,737,- 496 to Catlin; U.S. Patent 2,737,452 to Catlin et al.; U.S.

Patent 2,800,452 to Bondi et al.; application Serial No.

690,184, filed October 15, 1957; and application Serial No. 711,067, filed January 24, 1958.

The oils in which the additives of the invention may be incorporated are liquid hydrocarbon products such as those petroleum products boiling in the range between about 75 F. and about 900 F. Such products include gasolines, aviation turbojet fuels, kerosenes, diesel fuels, transformer oils, turbine oils, heating oils, and synthetic and mineral lubricating oils, etc. The additives are particularly effective in distillate fuels boiling in the range between about 75 F. and about 750 F. Such fuels include gasoline turbojet engine fuels, diesel fuels and heating oils which have particularly poor stability properties and require the use of the polymeric dispersant additives. Aviation turbojet engine fuels are defined by U.S. Military Specifications MIL-5624C, MIL-F-25524A, and MIL-F-25558A, and ASTM Specification D-1655-59T, and are generally referred to as JP-4, JP-S and JP6. Diesel fuels in connection with which the additives of the invention are useful are more fully described in ASTM Specification D97553T and may be used in stationary, marine and automotive type engines. Typical of the heating oils in which the additives may be employed are those described in ASTM Specification D39648T, particularly those in Grades 1 and 2 thereof. Gasoline in which the additives may be utilized include those described in ASTM Specification D43958T, Federal Specification W-G-76 and Federal Specification VVG-109.

The polymeric dispersant additives are generally employed in petroleum hydrocarbon products such as those described above in minor amounts sufficient to stabilize the oil and particularly in concentrations ranging from about 0.001% and about 1% by weight. Concentrations of from 0.001% to 0.05% are generally preferred.

The alkyl pyrrolidones may be incorporated into the fuels by dissolving them directly in the fuel or in a suitable solvent such as isopropanol, bu-tanol, benzene, xylol, isooctane, fuel oil, or the like and then adding the result ant concentrate solution to the oil in quantities sufficient to give the desired additive concentrations. If desired, additive concentrates containing both the polymeric dispersant stabilizing additive and the alkyl pyrrolidone compound in a suitable solvent may be prepared. Other additive materials commonly used in the products to which the concentrate and additive is to be added include rust inhibitors, lead scavenging agents, corrosion inhibitors, dyes, dye stabilizers, cetane improvers, antistatic additives, antiknock additives, and anti-icing additives such as an aliphatic glycol, for example, hexylene glycol and the like.

The persistence of the haze formed in oil upon contact with water is measured in Waring Blendor Haze Tests wherein a quantity of water, such as 5 milliliters of water, and a quantity of the oil, such as 500 milliliters of the oil, such as JP-4, with and without polymeric additives and the inventive additivesare mixed in a Waring Blendor for a period of five minutes; the oil-water mixture is then observed over a specified settlement time period, such as two hours. The amount of light which is transmitted through the oil under standardized conditions is measured or the haze and emulsification condition of the fuel is visibly observed during this time period. Where measured, the light transmission is expressed as a percentage of the total light emitted from the source. These tests have been found to be an extremely effective means for determining the degree to which haze is present in hydrocarbon oils.

The effectiveness of the present inventive combination may be ascertained by the following examples.

EXAMPLE 1 A premium alkyl leaded motor gasoline of the type commercially marketed was stabilized by the addition of about 0.015% by weight of a detergent terpolymer produced by the copolymerization at about 60 C. with a benzoyl peroxide catalyst of about 71.8 mole percent of vinyl acetate, 3.0 mole percent of maleic anhydride, 7.4 mole percent of ditallow fumarate and 17.8 mole percent of di-C -oxo fumarate to produce an oil soluble detergent polymeric additive of about 420 average molecular weight. Five hundred ml. of this gasoline containing the polymeric additive were mixed with ml. of water in the Waring Blendor Test without and with various amounts of N-methyl-Z-pyrrolidone and the percentage light transmission determined after two hours. The results of this experiment are tabulated in Table I.

Table I REDUCTION OF AQUEOUS HAZE IN POLYMER-CON- TAINING GASOLINE BY ALKYL PYRROLIDONES Percentage Light Transmission After Two Hours Vol. percent Concentration of N-methyl-Z- pyrrolidone EXAMPLE 2 The Waring Blendor test described above was duplicated with no alkyl pyrrolidone incorporated in the polymeric containing gasoline. The slow addition of about ml. or about 2.0% of N-methyl-Z-pyrrolidone immediately resulted in a fuel of completely visible clarity. The Waring Blendor test was then repeated employing a higher quantity of water with the gasoline, that is, ml. or about 3.0%. The subsequent addition of about 15 ml. or about 3.0% of N-methyl-Z-pyrrolidone was then required to achieve complete visibile clarity. The subsequent vigorous agitation for 5 minutes in the Waring Blendor test of the latter fuel composition containing the 3.0% alkyl pyrrolidone failed to affect the reappearance of the persistent aqueous haze condition.

The above test results demonstrate that the addition of an alkyl pyrrolidone into the fuel prior to water contact inhibits the formation of persistent haze while subsequent incorporation reduces haze conditions. The quality of alkyl pyrrolidone required to dehaze the fuel is dependent on the amount of water in contact, the amount of agitation encountered, and the degree of dehazing protection required.

EXAMPLE 3 A mineral lubricating oil having a kinematic viscosity in centistokes of 108 at 100 F. and 12 at 210 F., a viscosity index of 104 and containing about 5% by weight of the terpolymer prepared in Example 1 as a stabilizing additive gave kinematic viscosity in centistokes at 100 F. of 145 and at 210 F. of 16, and a viscosity index of 117. This lubricating oil is improved in aqueous haze 6 characteristics by the addition of minor amounts of N- ethyl-2-pyrrolidone.

EXAMPLE 4 A motor gasoline having a 50% ASTM distillation point of less than 210 F. and containing a minor amount of an alkyl lead antiknock agent is stabilized by the addition of about 0.01 weight percent of an oil soluble ashless copolymer prepared by the copolymerization in benzene at about 55 C. with a minor amount of a benzoyl peroxide catalyst of 14.6 mole percent of a di-C -oxo fumarate, 6.6 mole percent of a di-C -oxo fumarate, 4.0 mole percent of a ditallow fumarate, 71.3 mole percent of vinyl acetate, and 3.5 mole percent of maleic anhydride. This gasoline containing the said polymeric additive when contacted by water forms a persistent stable aqueous haze which is reduced by the subsequent addition of about 1.5 volume percent of 3-methyl-N-methyl-2- pyrrolidone.

EXAMPLE 5 The water tolerance properties of a turbojet engine fuel boiling between 275 F. and 480 F. and containing about 0.02 weight percent of a stabilizing additive of an oil soluble copolymer prepared by copolymerizing at about to C. in benzene in the presence of about 1% by weight of a benzoyl peroxide catalyst, 1 mole of vinyl acetate, 0.25 mole of isooctyl chloropropyleneoxy maleate, and 0.75 mole of mixed C C alkyl fumarate are improved by the addition of between 1.0 and 3.0% by volume of N-methyl-Z-pyrrolidone.

EXAMPLE 6 Aqueous haze is inhibited by the addition of minor amounts, less than 5.0% by volume, of 4-ethyl-N-methyl- 2-pyrrolidone to a heating oil boiling in the range between 324 F. and 643 F. and consisting of more than 10% by volume of a catalytically cracked stock and containing a stabilizing amount of an oil soluble copolymer prepared by the copolytmerization of 8 parts of Lorol methacrylate and 2 parts of beta diethylaminoethyl methacrylate.

EXAMPLE 7 A diesel fuel is stabilized by the incorporation therein of 0.005 weight percent of an oil soluble copolymer of 80 parts of lauryl acrylate and 20 parts of beta methylaminobutylvinyl ether and 0.08 weight percent of a mixture of tertiary alkyl primary amines derived from C to C polypropylene. To this fuel is added about more than 1.0 volume percent of N-methyl-Z-pyrrolidone to reduce the persistent aqueous haze forming tendency of the fuel.

EXAMPLE 8 A turbojet fuel (JP-4) is effectively protected against the long-time, i.e., over 6 hours, formation of opaque persistent aqueous haze by incorporating between 0.5 and 2.5 volume percent of N-methyl-Z-pyrrolidone in a JP-4 fuel containing a stabilizing amount (less than about 0.1 weight percent) of a terpolymer prepared by the copolymerization of about 40 mole percent vinyl acetate, about 20 mole percent of N-vinyl pyrrolidone, and about 40 mole percent lauryl fumarate.

EXAMPLE 9 A motor gasoline containing from 0.5 to 4.6 cc. of an alkyl lead antiknock agent, preferably tetraethyl lead, and which contains additionally about 0.05 weight percent of an ashless, oil soluble copolymer prepared by the copolymerization of about 80 mole percent of lauryl methacrytlate with about 20 mole percent of 3,5-dimethyl-N- vinyl pyrrolidone and which gasoline composition tends to form stable oil-in-water emulsions when contacted with an aqueous phase is effectively dehazed or demulsified after a two hour settlement period by the addition of between about 1.0 and 5.0 volume percent of N-methyl-Z- pyrrolidone.

From the foregoing examples, the remarkable effectiveness of alkyl pyrrolidones in reducing aqueous haze formation in hydrocarbon oils is demonstrated. The results are particularly surprising since polymeric additives are generally employed in small quantities but, tending to stabilize oil-in-water emulsions, are efiectively reduced or inhibited in haze stabilization by the addition of N- methyl-Z-pyrrolidone. The effectiveness of the additives of this invention permits a significant improvement in the marketability, appearance, and Water tolerance properties of petroleum products and simplifies the handling and the storage of such products.

What is claimed is:

1. A liquid hydrocarbon oil boiling between 75 and 900 F. containing a small amount sufficient to stabilize said oil of an oil soluble, ashless polymeric additive having a molecular weight of from 1,000 to 100,000 which upon contact with water promotes the formation of a persistent aqueous haze condition and to which has been added a minor amount suflicient to reduce the haze condition of an alkyl pyrrolidone wherein said alkyl radical contains from 1 to 4 carbon atoms.

2. A composition as claimed in claim 1 wherein said minor amount is suflicient to yield a light transmission of above 80% after a two hour settlement period.

3. A composition as claimed in claim 1 wherein said hydrocarbon oil is gasoline.

4. A composition as claimed in claim 1 wherein said haze-promoting polymeric additive is an oil soluble terpolymer prepared by the reaction of a vinyl ester of a short chain fatty acid, an unsaturated conjugated dibasic acid anhydride of from 4 to 5 carbon atoms, and an alkyl ester of an unsaturated conjugated C C dibasic acid of from 4 to 5 carbon atoms.

5. A composition as claimed in claim 1 wherein said hazepromoting polymeric additive is an oil soluble copolymer of an alkyl chloropropyleneoxy mixed ester of an unsaturated conjugated dibasic acid and a vinyl ester of a short chain fatty acid.

6. A composition as claimed in claim 1 wherein said haze-promoting polymeric additive is an oil soluble, nitrogen-containing addition type copolymer of an aminefree monomer containing one polymerizable ethylene linkage and an aliphatic hydrocarbon chain of from 8 to 18 carbon atoms with a monomer containing a nitrogen atom and one polymerizable ethylene linkage.

7. A composition as claimed in claim 1 wherein said composition contains additionally a tertiary alkyl primary amine in an amine to polymer ratio of from 2/1 to 18/ 1.

8. A liquid petroleum hydrocarbon boiling in the range between and 750 F. containing from about 0.001% to 1.0% by weight of a haze-promoting, ashless oil soluble polymeric additive of from 1000 to 100,000 molecular weight which, upon contact with water, promotes the formation of a persistent aqueous haze condition and to which has been added to reduce the persistence of said haze condition from 0.1 volume percent to 5.0 volume percent of an N-alkyl pyrrolidone wherein said alkyl radical contains from 1 to 3 carbon atoms per radical.

9. A composition as claimed in claim 8 wherein said pyrrolidone is N-methyl pyrrolidone.

10. A composition as claimed in claim 8 wherein said hydrocarbon is a turbojet engine fuel.

11. A composition as claimed in claim 8 wherein said hydrocarbon is gasoline.

12. A liquid petroleum hydrocarbon boiling in the range between 75 and 750 F. containing a small amount of an ashless, oil soluble polymeric detergent additive having a molecular weight of from 1,000 to 100,000 which, upon contact with water, promotes a persistent aqueous haze condition and containing between 1.0 and 3.0 volume percent of N-methyl pyrrolidone.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A LIQUID HYDROCARBON OIL BOILING BETWEEN 75 AND 900*F. CONTAINING A SMALL AMOUNT SUFFICIENT TO STABILIZE SAID OIL OF AN OIL SOLUBLE, ASHLESS POLYMERIC ADDITIVE HAVING A MOLECULAR WEIGHT OF FROM 1,000 TO 100,000 WHICH UPON CONTACT WITH WATER PROMOTES THE FORMATION OF A PERSISTENT AQUEOUS HAZE CONDITION AND TO WHICH HAS BEEN ADDED A MINOR AMOUNT SUFFICIENT TO REDUCE THE HAZE CONDITION OF AN ALKYL PYRROLIDONE WHEREIN SAID ALKYL RADICAL CONTAINS FROM 1 TO 4 CARBON ATOMS. 